Can it be that El Santo has stumbled upon the world’s first self-referential, post-modernist horror movie-- a movie, no less, that was shot more than 25 years before post-modernist self-referentiality as we know it today was even invented? Is it even possible to be self-referentially post-modern by accident? That might be pushing it a bit, but by the time I’m done talking about Black Friday, I think you’ll be able to see where I got such a screwy idea.

What we have here is another one of those 70-minute wonders the big studios used to crank out in the 40’s like Ford cranked out Model A’s. At first glance, it’s got a fairly standard mad scientist premise, but what its creators chose to do with that premise is curious indeed. Professor George Kingsley (Stanley Ridges, from The Phantom Speaks) teaches English literature at Newcastle College in what appears to be the Connecticut hinterland of New York City. One day, Kingsley has the misfortune to be crossing a road that two cars full of gangsters have chosen as the venue for their running gunfight. One of the cars suddenly careens off the road and plows into a storefront, running Kingsley down in the process. The driver of the car is a career criminal named Red Cannon. His back was broken in the crash, leaving him paralyzed from the waist down. Professor Kingsley came out rather worse: he took a hit to the head, and suffered serious brain damage. The doctors at Newcastle’s hospital can do nothing for either man. Cannon will never walk again and Kingsley will surely die within a few days. But Kingsley’s best friend, a surgeon by the name of Ernest Sovac (Boris Karloff), is rather more resourceful than the ones who worked on the two men when they arrived, and later that night, he comes to the hospital to perform, unbeknownst to anyone, a radical operation the technique for which he has been developing on animals for many years.

What Sovac does is to replace the damaged part of his friend’s brain with the corresponding piece of Cannon’s, passing off the resulting death of the latter man as being due to “complications” from his injuries. Sure enough, the operation saves the teacher’s life, but problems predictably develop almost immediately. As anyone who’s ever seen a mad scientist movie knows, the correct way to perform a brain transplant is to put the brain of the person you want to save into a new body-- not the other way around! Granted, Kingsley doesn’t have a whole new brain, but he’s got enough to change his personality, leading Sovac to the inescapable conclusion that his friend is carrying around at least a piece of Cannon’s mind with him. What makes this even more interesting than it would have been on its face is something Sovac read in the papers a few days after he performed the transplant. The gangsters who had been shooting at Cannon were his own men, who had learned that their leader was hiding a stash of half a million dollars, which he had no intention of sharing. It occurs to Sovac that Kingsley might now have some of the gangster’s memories in addition to the personality traits he has already exhibited, and he decides to take his friend to New York (Cannon’s old stomping ground) in the hope of digging up some of those memories-- the ones relating to the location of the loot in particular. (You could build a mighty fine mad lab with that much money in 1940, you know.)

When Sovac and Kingsley reach the city (they rent the very same rooms in the very same hotel that Cannon had used as a hideout), events prove the surgeon’s intuitions correct. Kingsley does indeed possess many of Cannon’s memories, though he doesn’t know why (nobody ever told him about the reason for his “miraculous” recovery), and he doesn’t say anything about a great deal of hidden money, either. What Kingsley does do is to begin Jekyll-and-Hyding, switching between his own personality and Cannon’s every time he goes to sleep-- if he nods off as Kingsley, he awakens as Cannon, and vice versa.

At first, the gangster is a bit dismayed to learn that he has been put into some other guy’s body. But once Cannon realizes the benefits that accrue to a criminal mastermind who everyone believes is dead, and whom no one would recognize even if they saw him, it’s only a matter of time before he starts acting on the realization. In no time at all, he’s using the anonymity afforded him by Kingsley’s body to aid him in getting revenge on his “killers,” starting small at first, but gradually working his way up the ladder to the gang’s new leader, Eric Mannay (Bela Lugosi, in what has to be the movie’s most startling casting gambit). Along the way, Cannon’s old girlfriend Sunny (Man-Made Monster’s Anne Nagel), along with Kingsley’s wife (Virginia Brissac, of Bewitched and The Mummy’s Tomb) and Sovac’s daughter (Anne Gwynne, from Weird Woman and House of Frankenstein), get caught up in the caper, which finally ends with the whole gang dead, Cannon’s personality subsumed in Kingsley’s, and Sovac in possession of the 500 grand. But wait-- back in Newcastle, the sound of a police siren sets off one of the few twist endings I’ve seen that actually added anything to the movie it brought to a close.

The most striking thing about Black Friday is that it feels like somebody did to the movie what Sovac did to Cannon and Kingsley. It plays like someone transplanted the brain of a crime melodrama into the body of a horror flick. This is that “accidental self-referentiality” I mentioned back in the first paragraph. For most of its brief running time, the film’s horror/sci-fi trappings are really beside the point, and Black Friday behaves like a straight-ahead gangster movie-- and quite a good one at that. But with all the brain-transplantation, personality-switching, and karmic retribution for meddling in God’s domain going on, there’s no question but that we’re supposed to take this as something like a film noir Frankenstein. It works better in crime melodrama mode; the mad science angle is handled pretty weakly, whereas Stanley Ridges does a great job playing a reptilian mobster, even if his victims have a tendency to blow the mood by screaming, clearly, at the top of their lungs as he strangles them. But Black Friday’s greatest strength may be its own brevity-- no matter how short your attention span is, there’s a limit to how bored you can get in an hour and ten minutes.